Field of the Invention
The present invention relates to ink-jet printers configured to jet ink onto a recording medium to print images.
Description of the Related Art
There are ink-jet printers adopting such a method as to jet ink respectively from a plurality of nozzles to print image while moving an ink-jet head having the plurality of nozzles in a predetermined scanning direction relative to a recording medium. Such printer prints the image on the recording medium by alternately carrying out one single movement of the ink-jet head in the scanning direction (to be also referred to below as a pass), and a transportation of the recording medium in a transport direction by a predetermined length.
However, due to some factors such as deviation in transported length and the like, the abovementioned printer may cause deviation in the transport direction between the image part printed in a previous pass and the image part printed in the successive pass. Such cases may give rise to non-uniform shading (white streaks and black streaks) in the shape of streaks extending in the scanning direction between the two image parts. Any occurrence of such non-uniform shading greatly lowers the quality of the image printed on the recording medium.
In this regard, there is known such a printer as is capable of suppressing occurrence of the streak shaped non-uniform shading mentioned above. This printer causes the scanning area of a previous pass to overlap partially with the scanning area of the successive pass in the transport direction of the recording medium. On top of that, it zigzag changes the border between the image part printed in the previous pass and the image part printed in the successive pass. Further, in the case of multicolor printing, each such border as mentioned above may be misaligned from another (i.e. differ in alignment with another) between the nozzle rows for different colors. By adopting such a printing method as described above, the streaks become less likely to be conspicuous between the image part printed in the previous pass and the image part printed in the successive pass. However, there is no knowledge about under what kind of conditions the above printing method is adopted.